Electrical beverage making apparatus

ABSTRACT

An electric coffee maker ( 2 ) comprises a first chamber ( 4 ), and a second chamber ( 6 ) arranged on top of the first chamber. A tube ( 8 ) extends down from the second chamber ( 6 ) into the first chamber ( 4 ) for transferring liquid between the two chambers. The base ( 20 ) of the first chamber ( 4 ) is provided with electric heater ( 24 ) and a thermally responsive control ( 46 ) is provided associated with the base ( 20 ) so as to be responsive to the temperature of the heater ( 24 ) or to a section of the base ( 20 ) for interrupting the power supply to or reducing the heating output of the heater ( 24 ).

BACKGROUND OF THE INVENTION

The present invention relates to electrical beverage making appliancesand in particular, but not exclusively to electric coffee makers.

A known type of coffee maker beverage type is known which comprises twochambers: a first chamber for receiving water to be heated; and a secondchamber which is seated on top of the first chamber and which receivesthe coffee grounds. The second chamber is in fluid communication withthe first chamber through a water transfer pipe which extends down fromthe second chamber into the first chamber. A separator arranged at thetop of the water transfer tube allows water to flow into and out of theupper chamber while retaining the coffee grounds. In use, the liquid inthe first chamber is heated externally, for example by a gas or spiritflame or an electric element arranged under the chamber. As water in thefirst chamber heats, the pressure in that chamber increases causing thewater in the first chamber to rise up through the transfer pipe into thesecond chamber where it infuses with the coffee grounds. Eventually, thelevel of liquid in the first chamber falls below the bottom of the tube,and transfer of liquid stops. The heating is then discontinued and thefirst chamber then cools so that steam will begin to condense on theinside of the lower chamber. When it does so, a partial vacuum iscreated in the first chamber which causes infused beverage to be suckedback down the tube through the separator into the first chamber. Whenall the beverage has been sucked down into the first chamber, the secondchamber can be removed and the beverage be served from the firstchamber.

Such an appliance is disclosed in GB 1,332,656. In that appliance, anelectric heating element or a gas flame is arranged under the firstchamber and controlled by a thermally responsive actuator arranged inthe second chamber. The actuator senses the temperature of theatmosphere in the second chamber and when it reaches a predeterminedtemperature either discontinues the electrical supply to the heatingelement or operates a valve in the gas supply to the gas flame.

One problem with the above arrangement is that it is difficult andexpensive as the actuator is arranged remotely from the heating sourcewhich means that connections have to be made between the two. Thisresults in unsightly and unnecessary housings or shrouds being providedin the apparatus and unnecessary expense. A further problem is that theheating of liquid in the first vessel is slow and inefficient and afterthe sensor has cut off the element considerable amounts of heat continueto flow from the heater into the apparatus.

DISCLOSURE OF THE INVENTION

The present invention seeks to overcome the above problems, and from afirst aspect, therefore, provides a beverage maker comprising:

a first chamber;

a second chamber arranged on top of said first chamber;

a tube extending down from said second chamber into said first chamberfor transferring liquid between the two chambers; wherein:

the base of said first chamber is provided with electric heating meansand thermally responsive control means are provided associated with thesaid base so as to be responsive to the temperature of the heating meansor a section of the base for interrupting the power supply to orreducing the heating output of the heating means.

Thus in accordance with the invention, the base of the first chamber isprovided with electrical heating means and power to the heater isinterrupted or the heating output thereof substantially reduced inresponse to the heater or a portion of the base reaching a predeterminedtemperature. This stops, or at least substantially reduces heating ofthe liquid in the lower chamber, so as to stop boiling. The firstchamber then cools, water begins to condense on the wall of the firstchamber and transfer of infused beverage from the second chamber willcommence.

This arrangement allows the liquid in the first chamber to be heatedefficiently, accurate control to be achieved and obviates the need forunsightly and cumbersome electrical connections between the first andsecond chambers.

The control means of the invention may be arranged to operate in one ofa number of ways. In a first embodiment, the control means is configuredand arranged so as to detect when a portion of the base of the firstchamber boils dry, which indicates that a predetermined amount of theliquid in the first chamber has been transferred to the second chamber.This condition can easily be detected by a suitable thermal sensor inthermal contact with the base or the heater since in the absence ofwater which cools the base or heater, the temperature of the base orheater will rise very quickly.

In an arrangement as described above, preferably only a specifiedportion of the base or heater boils dry, such that water still coversthe remainder of the base.

This may be achieved in a number of ways. For example the base or heatermay be provided with a locally raised region which boils dry. Thisregion could, for example be formed as a raised region of a heater platesuch as is disclosed in Applicant's GB 2,316,847 to which reference canbe made for further detail. A suitable sensor may then be arranged underthe raised region which will become exposed in advance of the remainderof the base.

In an alternative arrangement, the base or heater of the first chambermay be generally planar, but arranged to slope such that a peripheralregion thereof will become exposed and overheat as the liquid level inthe first chamber drops as liquid is transferred to the second chamber.A suitable sensor may be arranged under that part of the base or heater.

Preferably, however, the base is provided with a region which isseparated from the remainder of the region by a raised wall. Mostpreferably, the wall surrounds the entire heated region of the base.This wall forms a reservoir of water above the heater in the base, andit will be appreciated that the higher is this wall, the longer it willtake for water within the reservoir to evaporate, and thus for thecontrol to operate. This allows a mechanism by which the beverageinfusion time can be varied since that is dependent upon how long thewater remains in the second chamber. This is, in turn dependent uponmaintaining the pressure in the first chamber, which in turn depends onthe continued boiling of liquid in the first chamber. Thus in apreferred embodiment, the wall is adjustable in height to allow foradjustment of the beverage infusion time.

A further way in which the infusion time can be varied is by varying thepower of the heating element. If the element is heats at low power, thenit will take longer for the liquid in the reservoir to boil away,thereby maintaining the vapour pressure in the first chamber for alonger period, thereby keeping the hot water in the second chamberinfusing for a longer period of time. Conversely, if the element heatsat high power, then liquid in the reservoir will boil away more quickly,thereby reducing the infusion time. In one embodiment of the inventiontherefore, means may be provided for varying the power of the heatingelement. Means for achieving such a power variation will be readilyconceivable by the skilled person and are thus not described in furtherdetail here.

A yet further way in which the infusion time could be varied would be tohave an additional heater which heats a portion of the base which wouldstill be covered by water after the main heating element has beenswitched off. This element need not be particularly high power, say 50W, but even at that low power it would generate sufficient vapour tomaintain the vapour pressure in the first chamber. The additional heatercould be switched off after a predetermined time to bring the infusionperiod to an end.

In the embodiments described above, the temperature of the base orheater can be sensed in any convenient manner. Preferably, however, thetemperature is sensed using a thermomechanical sensor such as abimetallic actuator arranged in good thermal contact with the base orheater. In the preferred embodiment, a pair of actuators most preferablyoperable at substantially same temperature can be employed to sense theoverheating condition.

A suitable control of this type is disclosed in Applicant's WO95/34187.Such a control is equally suitable for engagement with heaters havingsheathed elements or with thick film heaters.

A possible disadvantage with the above control arrangement is that withrepeated boiling dry of an area of the lower chamber base, scale may bedeposited on the base, which would be unsightly. In an alternativearrangement, therefore, the control means is configured and arranged tosense boiling of the liquid in the first chamber via a portion of thebase of the vessel. This can be done by sensing the localized boilingdry of a section of the heater, for example by using a system asdisclosed in GB 2,283,155. Preferably, however, boiling is sensed bymeans of a system as disclosed in Applicant's WO96/01875 and WO98/36616,or in unpublished United Kingdom Patent Application No. 9805751.6 whichfor the purposes of sufficiency is attached as Appendix I hereto.

In accordance with such systems, a relatively low volume sump will beprovided in the heated base of the first chamber, and a thermallysensitive actuator mounted in thermal contact with that sump. Whenliquid is heating in the first chamber, the temperature of the liquid inthe sump lags behind that in the main body of liquid, as there is littleconvection within the sump. However, when the liquid in the first vesselboils, the liquid in the sump is quickly displaced and the sumptemperature quickly rises. This rise in temperature can be sensed bysuitable means.

Depending on the boiling time required, the actuator may be mounted inclose thermal contact with, or thermally more remote from the sump. If avariable boiling time is required (to vary the infusion time—the longerthe boil, the longer liquid will be held ion the second chamber), meanscan be provided to increase or decrease the length of time it takes theactuator to reach operating temperature. Such means might comprise heatsinks which could selectively be introduced into the thermal pathbetween the sump and the actuator.

A control arrangement of the above type has the additional advantagethat the first chamber can be used as a traditional kettle, since itwill switch off when boiling is detected, irrespective of the presenceor absence of a further chamber. All that is required is that thepouring spout of the first chamber is configured such that it maysealingly receive the second chamber with its depending tube.

This is in itself a novel arrangement, and from a further aspect theinvention provides a water heating vessel comprising a water receivingchamber, the base of said chamber being provided with electric heatingmeans, and further comprising thermally responsive control means areassociated with the said base for sensing when the water in the chamberis boiling so as to interrupt the power supply to or reduce the heatingoutput of the heating means, said chamber further being provided with apouring spout which is adapted and arranged sealingly to receive theneck of an infusion receiving chamber.

Preferably, the spout is centred on a vertically extending axis, andpreferably is tapered to receive a tapering seal such as a rubber bung.If necessary, a suitable spout cover may be supplied to at leastpartially close the spout when it is being used as a kettle.

The heating means used in an appliance in accordance with the inventionmay comprise a sheathed heating element attached to the underside of thebase, for example through a heat diffusion plate. Such constructions arewell known in the art and so need not be described further here.

In a preferred embodiment, however, the heating means comprises aso-called thick film heater provided on the base. Such heaters arebecoming more commonly in the water heating art and comprise aelectrically resistive heating track deposited on an insulatedsubstrate. Typically the insulated substrate is provided by aninsulating layer laid down on a stainless steel plate. Examples of suchheaters are disclosed, for example, in WO 98/36618 and WO96/17496.

The heater may be provided over the whole of, or merely a part of thebase of the first chamber. In the preferred embodiment, the heater isformed as a separate unit mounted in a suitable aperture formed in thebase of the first chamber.

The heating means of the apparatus may comprise an element which keepsthe infused beverage in the first chamber warm after the control of theapparatus has operated. This “keep warm” element may be provided in anumber of ways.

In a first arrangement, a keep warm element may be provided which isseparate from the main heating element. This keep warm element may beenergised the whole time the main heating element is energised or may beswitched on only after the control has operated to switch off the mainheating element. In an alternative arrangement, the keep warm elementmay be connected into series with the main heating element after boilinghas been sensed. The resistance of the main element (which wouldtypically be an order of magnitude smaller than that of the keep warmelement) means that very little heat is generated in the main elementpart when so connected.

The keep warm element may be arranged to cycle, for example in a manneras described in WO97/04694. In such an arrangement the temperature ofthe base would be monitored and the keep warm element operated inresponse to the base temperature. This arrangement is particularlysuited to use with sheathed heating elements. However, it has thedisadvantage that the temperature of the base may be such as to causelocalized boiling of the beverage in the first chamber during theheating bursts, which may be detrimental to the flavour of the beverage.

Preferably, therefore, the keep warm element is energized continuouslyafter operation of the vessel control, but at such a power level thatwill not cause the beverage in the first chamber to boil. The powerrequired to achieve this can be easily determined empirically by theskilled person. In this case, the element will probably be a thick filmtype heater whose power level and power density can very easily betailored to meet particular requirements. Typically, however, one mighthave a main heating element rated at 1500 W at a Watts density of 50-150Wcm⁻² and a keep warm element rated at 50 W at a watts density of 10Wcm⁻². A general track arrangement and switching arrangement suitable inprincipal for achieving such a heating regime is disclosed inGB9805751.6.

It is believed that the above arrangement constitutes an invention inits own right, so from a further aspect the invention provides abeverage maker comprising:

a first chamber;

a second chamber arranged on top of said first chamber;

a tube extending down from said second chamber into said first chamberfor transferring liquid between the two chambers; wherein:

the base of said first chamber is provided with electric heating meansfor keeping infused beverage in the first chamber warm, the heatingmeans being rated such that it will not cause boiling of the infusedbeverage in the lower chamber.

The lower chamber is preferably configured as a cordless arrangementwhereby it my be removably positioned on a power supply stand. Thisconsiderably facilitates pouring of the beverage.

BRIEF DESCRIPTION OF THE DRAWINGS

Some preferred embodiments of the invention will no be described by wayof example only with reference to the accompanying drawings in which:

FIG. 1 shows a schematic partial cross section through an appliance inaccordance with a first embodiment of the invention;

FIG. 2 shows a view along line II—II of FIG. 1, with the heater removedfor clarity;

FIG. 3 shows a heater layout for use in the embodiment of FIGS. 1 and 2;and

FIG. 4 shows a further embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIG. 1, a coffee making appliance 2 comprises a first,lower, water receiving chamber 4 and a second, upper, coffee receivingchamber 6. The lower chamber 4 is preferably formed from a plasticsmaterial most preferably a transparent or translucent plastics materialand the upper chamber 6 which is preferably of glass.

The upper chamber 6 is formed with a tube 8 which extends down into thelower chamber 4. The upper chamber 6 is supported on the lower chamber 4by a sealing bung 10 which is mounted in the spout 12 of the lowerchamber 4. The bung 10 is provided with a central bore for receiving thetube 8. A separator 16 is supported in the lower part of the upperchamber 6 and permits heated water to enter the upper chamber 6 from thelower chamber 4 and thereafter to allow infused beverage to enter thelower chamber 4 from the upper while retaining coffee grounds.

The lower chamber is provided with a handle 18 to facilitate pouring ofthe coffee therefrom.

The lower chamber 4 has a base 20 which has an electrically heatedportion 22 formed by a thick film heater 24. The base is formed as aplastics moulding 26, for example of nylon, having a central circularopening 28 for receiving the heater 24, with an upstanding wall 30arranged around the opening 28 for a purpose which will be describedfurther below. The moulding 26 is also formed with a well 30 forreceiving the lower end of the tube 8.

The moulding 26 is mounted to close the bottom of the lower chamber 4,with a seal 32 arranged therebetween. The moulding may be retained inthe lower chamber by any suitable means such as bonding or welding.

The thick film heater 24 is supported in a silicone rubber sealing ring34 which is clamped into the opening 28 by a clamping ring 36 which hasa number of bores around its periphery to receive fastening screws whichengage in bores (not shown) in the moulding 26.

The thick film heater 24 for use in the above embodiment is shown inFIG. 3. It comprises, in a known manner, a circular stainless steelplate of 0.9 to 1 mm thickness provided with an insulating layer and aresistive heating track 40, which in use faces downwardly. The track 40is rated at about 1500 W. Electrical contact pads 42 are provided at therespective ends of the heating track as shown, and is provided withthree upstanding studs 44 for receiving a thermally sensitive controlunit 46.

The thermally sensitive control unit 46 is mounted to the underside ofthe heater 26. The control unit 46 is the applicant's commerciallyavailable U28 control unit which comprises, inter alias, a pair of snapacting bimetallic actuators, 50 operable at substantially the sametemperature and which in use will engage regions 52 of the heater 26when the control unit 46 is mounted in position. It also comprises apair of spring contacts 54 which make contact with the contact pads 42of the heater, and an on/off lever 56. The U28 is itself an adaptationof the Applicant's U18 control for use with thick film heaters. The U18is described at length in WO 95/34187 and reference should be made fordetails of its mode of operation.

The control unit 46 also incorporates a cordless electrical connectorwhich will allow power to be supplied to the heater 26 when the lowervessel is placed on a power supply stand 60.

The mode of operation of the above embodiment will now be described.Firstly, coffee grounds are placed in the upper chamber 6 and water inthe lower chamber 4. The lower chamber is then placed on the powersupply stand 60 and the unit switched on by the lever 56.

The water in the lower chamber will begin to heat and when itstemperature reaches typically about 60° C. the pressure in the lowerchamber 4 has risen sufficiently to begin forcing the water up the tube8 through the separator 16 and into the upper chamber 6. Eventually, thewater in the lower chamber 4 will begin to boil at which point waterwill very quickly rise through the tube 8 and into the upper chamber 6.The level of water in the lower chamber 4 will then fall very rapidlyfall to the upper edge of the wall 30 around the heater 26. This wall 30acts as a reservoir to contain a pool of water which will continue toboil for a period of time determined by the height of the wall 30.Effectively, the higher the wall 30 the longer the liquid in thereservoir will boil which in turn means the longer will be maintainedthe pressure in the lower chamber 4. This in turn means that the waterwill remain for a longer period in the upper chamber 6, thereby givinglonger infusion and a stronger brew.

When the reservoir has boiled dry, the heater 26 will rise very quicklyin temperature and this rise is detected by one or both of the actuators50 of the control unit 46 which will then operate in a known manner toswitch off the power supply to the heater 26.

In time, the steam in the lower chamber 4 will begin to condense therebyforming a vacuum in the lower chamber 4 which will suck the infusedbeverage from the upper chamber 6 through the separator 16 back into thelower chamber 4. The upper chamber 6 can then be removed and coffeedispensed from the lower chamber.

Turning now to FIG. 4, a second embodiment of the invention is shownschematically. This embodiment operates on the principal of detectingboiling of liquid within the lower chamber 4 through a low volume sumpprovided in the base of the lower chamber 4, rather than by the boilingdry of a portion of the base.

In this particular embodiment, an integrated control and heater unit 100of the type disclosed in the Applicant's International patentapplication no. WO99/48333 is mounted in the base of the lower chamber4. In particular, the unit 100 is mounted to a moulding 102 which isretained in the bottom of the lower chamber 4 in the same manner as thein the earlier embodiment.

As can be seen with reference to the description of WO99/48333, the unit100 comprises a heater plate on its upper surface 104 which includes arelatively small volume sump 106 (shown schematically in FIG. 4). Abimetallic actuator is arranged in thermal contact with the externalbase of the sump such that when liquid in the vessel begins to boil, thewater in the sump (which up to that point has remained cool relative tothe bulk of water on the lower chamber 4) is displaced by hotter waterand the sump temperature rises. This rise in temperature is sensed bythe bimetallic actuator to discontinue boiling of the water.

In this embodiment of the invention, as in the earlier embodiment, aswater is heated in the lower chamber 4, it will begin to rise throughthe tube 8 into the upper chamber 6, slowly at first and then quiterapidly when boiling occurs. The boiling of the water in the lowerchamber 4 is detected by the control unit 100 and after a given time(determined largely by the thermal path between the sump and theactuator), the main heating effect is discontinued.

After some time water will condense in the lower chamber 4 and theinfused beverage be sucked back into the lower chamber 4 from where itmay be dispensed.

In the integrated heater and control unit disclosed in WO99/48333, afterboiling has been discontinued, a keep warm element (which actuallyincludes the main heating element) is energised to keep liquid warm. Inthat arrangement, the keep warm element is about 30 W and isconcentrated in one region so as to cause localised boiling foraesthetic effect. In the present embodiment of the invention, such akeep warm element is still preferably provided, although ideally thekeep warm element will be spread out over a larger area to reduce thewatts density thereof so as not to cause localised boiling in the lowerchamber 4 which might harm the flavour of the coffee.

It will be seen that the above described second embodiment of theinvention has the advantage that the lower chamber 4 can also be used asan ordinary kettle, simply by removing the upper chamber 6 and bung 10.The kettle will still switch off after liquid boils in the lower chamberirrespective of whether the upper chamber is provided.

It will be noted that the spout 12 of the lower chamber is arrangedgenerally vertically and is tapered to receive the sealing bung 10 forthe upper chamber. If necessary, means may be formed on the spout toassist in retention of the bung 10. A separate spout cover may beprovided with the appliance to at least partly cover the spout when thelower chamber 4 is being used as a kettle.

It will be appreciated that the above description is by way of exampleonly and that modifications may be made to the embodiments describedwithout departing from the scope of the invention. For example in theembodiment of FIGS. 1 and 2, the beverage infusion time may be varied ina number of ways. For example, the height of the wall 30 surrounding theheater could be made variable by a suitable mechanism. Alternatively,the heating power of the heating element may be varied so that thereservoir defined inside the wall 30 takes a longer or shorter time toboil dry. This could be achieved, for example by selectively connectingfurther resistance in series with the heating element.

In a yet further arrangement, an additional heater could be positionedin the base of the well 31 defined in the base moulding 26. Once theliquid in the reservoir defined within the wall 31 boils dry, there willstill be liquid within the well 31, and if this is heated after the mainheating element is turned off, then it will maintain to some extent thepressure in the lower chamber 4 so as to keep the water in the upperchamber 6 for longer. The additional element can be deenergised after apredetermined or variable time period. Such a heater could also beenergised to act as a keep warm element to keep the infused beveragewarm after it has returned to the lower chamber 4.

What is claimed is:
 1. A beverage maker, comprising: a first chamberhaving a base that includes an electronic heating means and a controlmeans; a second chamber arranged on top of the first chamber; a tubeextending down from the second chamber into the first chamber fortransferring liquid between the two chambers; wherein the control meansis thermally responsive to the temperature of the electronic heatingmeans or to a section of the base, and the control means is operable tointerrupt a power supply to the electronic heating means or to reducethe heating output of the electronic heating means when a portion of thebase of the first chamber boils dry; and wherein the portion of the basethat boils dry is separated from the remainder of the base by a raisedwall to define a reservoir of liquid that must boil away before thecontrol means operates.
 2. The beverage maker of claim 1 wherein theraised wall surrounds the entire heated region of the base.
 3. Thebeverage maker of claim 2 further comprising a thermal sensor in thermalcontact with one or both of the base of the first chamber and theelectronic heating means.
 4. The beverage maker of claim 3, furthercomprising means for adjusting the infusion time of a beverage in thesecond chamber.
 5. The beverage maker of claim 4 wherein the means foradjusting the infusion time of a beverage in the second chamber includesone of a plurality of raised walls, each having a different height,wherein each different height raised wall creates a different infusiontime for the beverage in the second chamber.
 6. The beverage maker ofclaim 4, wherein the means for adjusting the infusion time of thebeverage in the second chamber comprises means for varying the power ofthe electronic heating means.
 7. The beverage maker of claim 6, whereinthe means for adjusting the infusion time comprises a secondary heaterthat is positioned relative to the base so that the secondary heaterheats a portion of the base which is still covered by water after theelectronic heating means has been de-energized.
 8. The beverage maker ofclaimed 7, wherein the electronic heating means comprises a sheathedheating element attached to an under side of the base.
 9. The beveragemaker of claim 7, wherein the electronic heating means comprises a thickfilm heater provided on the base.
 10. The beverage maker as claimed inclaim 9, wherein the electronic heating means is formed as a unitmounted in an aperture formed in the base of the first chamber.
 11. Thebeverage maker as claimed in claim 10 comprising a keep-warm heatingelement that keeps the infused beverage in the first chamber warm afterthe control of the apparatus has operated.
 12. The beverage maker ofclaim 11 wherein the keep-warm heating element is a separate element tothe electronic heating means.
 13. The beverage maker of claim 12 whereinthe keep-warm heating element is energized at such a power level as notto cause the beverage in the first chamber to boil.
 14. The beveragemaker of claim 1, further comprising a thermal sensor in thermal contactwith one of the base of the first chamber or the electronic heatingmeans.
 15. The beverage maker of claim 14, further comprising means foradjusting the infusion time of a beverage in the second chamber.
 16. Thebeverage maker as claimed in claim 15 comprising a keep-warm heatingelement that keeps the infused beverage in the first chamber warm afterthe control of the apparatus has operated.
 17. The beverage maker ofclaim 1, further comprising means for adjusting the infusion time of abeverage in the second chamber.
 18. The beverage maker as claimed inclaim 17 comprising a keep-warm heating element which keeps the infusedbeverage in the first chamber warm after the control of the apparatushas operated.
 19. The beverage maker of claim 17, wherein the means foradjusting the infusion time of a beverage in the second chamber includesone of a plurality of raised walls, each having a different height,wherein each different height raised wall creates a different infusiontime for the beverage in the second chamber.
 20. The beverage maker ofclaim 17, wherein the means for adjusting the infusion time of thebeverage in the second chamber comprises means for varying the power ofthe electronic heating means.
 21. The beverage maker of claim 17,wherein the means for adjusting the infusion time comprises a secondaryheater that is positioned relative to the base so that the secondaryheater heats a portion of the base which is still covered by water afterthe electronic heating means has been de-energized.
 22. The beveragemaker of claim 1, wherein the raised wall has a height selected tocreate a predetermined infusion time for the beverage in the secondchamber.
 23. The beverage maker of claim 1, further comprising means forvarying the power of the electronic heating means.
 24. The beveragemaker of claim 1, further comprising a secondary heater that ispositioned relative to the base so that the secondary heater heats aportion of the base which is still covered by water after the electronicheating means has been de-energized.
 25. The beverage maker as claimedin claim 1, comprising a keep-warm heating element that keeps theinfused beverage in the first chamber warm after the control of theapparatus has operated.
 26. The beverage maker of claim 25 wherein thekeep-warm heating element is energized at such a power level as not tocause the beverage in the first chamber to boil.
 27. A beverage maker,comprising: a first chamber having a base that includes a firstreservoir and a second reservoir; a first reservoir heater disposedadjacent the first reservoir; a second reservoir heater disposedadjacent a second reservoir; a second chamber in fluid connection withthe first chamber; a passage extending between the first chamber and thesecond chamber for transferring liquid between the two chambers; acontroller that is thermally responsive to the temperature of the firstreservoir heater or to the temperature of a section of the base, whereinthe controller is operable to interrupt a power supply to the firstreservoir heater or to reduce a thermal output of the first reservoirheater when the first reservoir boils dry.